The present invention provides an oxygen sensor adapted to contact exhaust gases, particularly of internal combustion engines which are ultimately used as part of the control of the fuel-air ratio, thereby controlling the emission content of the exhaust gas. The sensor of the present invention has an improved construction, including a heating element.
The basic prior art sensor of which the present invention is an improvement is of the type disclosed in German disclosure document OS 2 307 451. The sensor disclosed in the German publication does not include a heater element.
U.S. Pat. No. 3,546,086 discloses an electrochemical sensor which includes a heater element in the inner space of the closed end tubular solid electrolyte. The sensor disclosed in this patent has the design disadvantage that the inner electrode or the electrical contact to said electrode located in the inner space of the solid electrolyte requires an expensive coating on the interior surface of the tubular solid electrolyte.
It is an object of the present invention to provide an improved oxygen sensor containing a heater element which is economic in terms of materials and in terms of construction leading to an improved product.